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Biomedical subjects

A Takao

Publications and source records attributed to A Takao.

At least 73 records · Page 4Linked to original sources
PubMed1992

Effects of BY-1949 on evoked responses of cortical blood flow and Meynert neurons.

The effects of BY-1949, a novel dibenzoxazepine derivative, injected into the cerebral ventricle on noxious stimulus-induced responses of regional blood flow in the cortex and neuronal activity in the nucleus basalis of Meynert were studied in male rats. These induced responses were markedly enhanced by administration of BY-1949 (16.4 +/- 0.5 ng/100 g, S.E.M.). These data indicate that BY-1949 acts on the central nervous system to modulate the response to a noxious stimulus of regional cerebral blood flow and neuronal activity in the nucleus basalis of Meynert.

Action Potentials↗
PubMed1992

Cellular retinoic acid binding protein type II was preferentially localized in medium and posterior parts of the progress zone of the chick limb bud.

The expression and distribution of cellular retinoic acid binding protein II (CRABP II) was examined in chick limb buds. CRABP II was detected in the limb buds at Hamburger and Hamilton (1) stage 21 and the amount of CRABP II was gradually increased during stages 21-27 and thereafter decreased. CRABP II was mainly located in the progress zone, and the dorsal and ventral premuscular mass in the proximal region of the limb buds at stage 23. CRABP II was preferentially localized in the medium and posterior parts rather than the anterior part of the progress zone; The content of CRABP II in the medium and posterior parts was 8-9 times more than that in the anterior part.

Animals↗
PubMed1992

Imperforate tricuspid valve with dysplasia of the right ventricular myocardium, pulmonary valve, and coronary artery: a clinicopathological study of nine cases.

Nine cases of imperforate tricuspid valve associated with dysplasia of the right ventricular myocardium, pulmonary valve, and right coronary artery are described. The mean frontal QRS axis of the electrocardiograms did not indicate left axis deviation in seven of the nine. Two-dimensional echocardiograms showed an imperforate tricuspid valve, normally aligned atrioventricular septum, and an irregular-shaped right ventricular cavity with a thin wall. In three cases with absence of the pulmonary valve, pulsed Doppler echocardiograms of the right ventricular outflow tract revealed antegrade flow during systole and retrograde flow during diastole, and selective angiography through a persistent ductus arteriosus showed retrograde filling of the blind-ended right ventricular cavity via the main pulmonary artery. Necropsy examinations showed an imperforate tricuspid valve with a thin-walled aneurysmal right ventricle in all six cases examined. Pulmonary atresia was observed in two cases, and the absence of the pulmonary valve in four. The right coronary artery was hypoplastic in four cases and absent in two. A shunt operation should be carried out in early infancy to prevent hypoxia after closure of the ductus arteriosus.

Abnormalities, Multiple↗
PubMed1992

Effect of caffeine on expression of cardiac myosin heavy chain gene in adult hypothyroid and fetal rats.

Changes in cardiac myosin heavy chain (MHC) gene expression and isozyme transitions have been shown to be caused by developmental changes, hemodynamic overload, or the activity of various hormones. In this study, to examine whether caffeine, which has teratogenic effects on the fetal cardiovascular system, causes the distribution of cardiac MHC phenotype and, if so, to evaluate the mechanisms of the distribution of cardiac MHC phenotype by caffeine, we examined the effects of caffeine, theophylline, and cAMP on the cardiac MHC isoform transitions at the gene and protein levels using hypothyroid adult rats. Furthermore, we examined the expression of alpha- and beta-MHC gene in cardiac muscles of fetuses whose dams had received caffeine. The results showed that caffeine, theophylline, and cAMP caused accumulations of alpha-MHC mRNA and MHC isozyme V1. Furthermore, in the fetal hearts, it was recognized that caffeine induced an accumulation of alpha-MHC gene expression, as was also seen in the dams. However, this effect of caffeine on the heart was stronger in the fetus than in the dam. Intracellular cAMP concentration was increased by the administration of caffeine, theophylline, or cAMP, and the levels showed a positive correlation with those of alpha-MHC mRNA. These results suggest that the induction of alpha-MHC mRNA expression by the administration of caffeine may be induced by an increase in intracellular cAMP concentration.

Aging↗
PubMed1991

Complete sequence of human cardiac alpha-myosin heavy chain gene and amino acid comparison to other myosins based on structural and functional differences.

We have obtained the 5820 nucleotide sequence encoding all 1939 amino acids of the human cardiac alpha-myosin heavy chain (alpha-MHC), as established by dideoxy sequencing of cloned cDNA, genomic DNA and polymerase chain reaction (PCR) amplification products. This sequence represents overlapping fragments of the entire coding sequence. Amino acid sequence comparison of the human cardiac alpha-MHC with the published human cardiac beta-MHC have demonstrated that there are, at least, 7 isoform-specific divergent regions, including functionally important binding protein-related sites such as ATP, actin and myosin light chain. It has been reported that in the rat, there are 8 isoform-specific divergent regions. The 7th divergent area (residue area 1633-1657, which is thought to mediate thick filament formation) in the light meromyosin region in the rat is not apparent in the human. The amino acid compositions of cardiac alpha- and beta-MHCs in the human and the rat, and human embryonic skeletal muscle and chicken gizzard smooth muscles were compared. Amino acid sequences in cardiac alpha- and beta-MHCs in the human and the rat are well conserved. In the head portion, the amino acid composition divergence of human cardiac alpha-MHC is ranked between rat cardiac alpha-MHC and human cardiac beta- or rat cardiac beta-MHC; human skeletal muscle MHC is the most divergent of the myosin isoform examined. These data predict that human cardiac alpha-MHC may have undergone evolutionary changes toward obtaining the biochemical and physiological properties of cardiac beta-MHC.

Amino Acid Sequence↗
PubMed1991

Visceroatrial heterotaxy syndrome in the NOD mouse with special reference to atrial situs.

Following the onset of diabetes mellitus (DM) in the NOD mouse, diabetic dams have many offspring with severe anomalies, especially with visceroatrial heterotaxy syndrome. The purpose of the present study is to analyze this syndrome with special reference to atrial situs. The fetuses from a colony of NOD mice in our laboratory were divided into two study groups: Group A included fetuses from dams before the onset of DM and group B included fetuses from dams with overt DM before day 8 of pregnancy. The fetuses which had cardiac anomalies with viscero-atrial heterotaxy were classified into four subtypes according to the atrial morphology, i.e., "incomplete situs solitus" (or solitus-like), "incomplete situs inversus" (inversus-like), right isomerism, and left isomerism. Group A (671 fetuses) included only one case with right isomerism (0.15%) and four cases with left isomerism (0.6%). Group B (158 fetuses) had 57 fetuses with heterotaxy syndrome (36.1%), including 20 cases with solitus-like, 6 with inversus-like, 30 with right isomerism, and one with left isomerism. A tendency for right isomerism to occur was found in fetuses with solitus-like and inversus-like anomalies. These results show that the maternal DM in this mouse had an influence upon the morphological mechanism determining right isomerism of visceroatrial heterotaxy syndrome. Thus this syndrome in the NOD mouse is equivalent to asplenia in humans, and it may be useful in elucidating the mechanism of the human syndrome.

Animals↗
PubMed1991

Effect of partial Na pump and Na-H exchange inhibition on [Ca]i during acidosis in cardiac cells.

This study investigated the effects of partial Na pump inhibition and Na-H exchange inhibition on contractile function, intracellular pH (pHi), and intracellular Ca concentration ([Ca]i) during intracellular acidosis, using the fluorescent dyes 2',7'-bis(carboxyethyl)-5,6-carboxyfluorescein and fura-2 in isolated cardiac cells of adult rabbits. Intracellular acidosis with normal extracellular pH was induced by an NH4Cl (10 mM) prepulse technique. A nontoxic concentration (0.5 microM) of ouabain was used to inhibit the Na pump. 5-(N-ethyl-N-isopropyl)amiloride (EIPA) was used to inhibit Na-H exchange. In both the absence and presence of ouabain, pHi fell transiently and then recovered after removal of NH4Cl. Ouabain did not alter the pHi changes observed after removal of NH4Cl. Diastolic and systolic [Ca]i increased during acidosis after NH4Cl removal. In the presence of ouabain, the increase in [Ca]i during acidosis was greater than that in the absence of this drug. Ouabain enhanced the recovery of contractile function during acidosis. In both the absence and presence of ouabain, Na-H exchange inhibition by EIPA reduced the recovery of pHi and mechanical function and the increase in [Ca]i, which were normally observed after NH4Cl removal. These data suggest that in adult rabbit myocytes the Na pump inhibition enhances the increase in [Ca]i during acidosis, and the Na-H exchange inhibition reduces it. The [Ca]i increase during acidosis may be in part due to the altered Na-Ca exchange, which in turn results from the increased Na-H exchange.

Acidosis↗
PubMed1991

Adaptational changes of MHC gene expression and isozyme transition in cardiac overloading.

Distribution of cardiac myosin heavy-chain (MHC) isozymes is regulated during development by hemodynamic change and hormonal stimuli. To understand the evolution of cardiac hypertrophy and the underlying processes, the interaction between acute or chronic cardiac over-loading and serum thyroid hormone levels was studied. Biochemical, physiological, and pathological studies were performed using coarctated (Coa) rats with or without administration of thyroid hormone (Thy) and on sham-operated (Sham) rats and normal rats with or without administration of Thy. The results showed that 1) although serum Thy levels in Coa and Sham rats were nearly the same at all timing points, a significant induction of beta-MHC mRNA and isozyme occurred in Coa rats; 2) in Coa rats where Thy was administered, there was no increase in beta-MHC mRNA and isozyme as seen in Coa rats, and this level was nearly the same as in Sham rats, whereas serum Thy levels were significantly high, as in the normals with administration of Thy; and 3) 77 days after surgery, the hypertrophy was completed, judging from pathological findings at this time, and beta-MHC mRNA and isozyme reached similar levels in all groups, except for the normals with administration of Thy. These results demonstrate the following: 1) the MHC isoform transitions induced by pressure overload are not induced by decreases in serum Thy levels, and the regulation of MHC gene expression is responsive to other triggers in addition to Thy; and 2) the first adaptational process of the heart to hemodynamic overload is the MHC isoform transition, and the second adaptational process of that is the hypertrophy itself.

Adenosine Triphosphatases↗
PubMed1991

A quantitative analysis of hemodynamic effects of the right ventricle included in the circulation of the Fontan procedure.

BACKGROUND: Right heart hemodynamics were analyzed with a catheter-mounted velocity meter in seven patients after direct atrioventricular anastomosis for Fontan procedure (RV group) and were compared with those obtained in eight patients after direct atriopulmonary anastomosis (RA group). METHODS AND RESULTS: In the RV group, cardiac output was 2.7 +/- 0.6 l/min/m2; mean right atrial and pulmonary artery pressures were both 13 +/- 3 mm Hg; mean pulmonary artery wedge pressure was 7 +/- 5 mm Hg; left ventricular end-diastolic volume, determined angiographically, was 129 +/- 40% of normal; and its ejection fraction was 0.50 +/- 0.09. In the RA group, data were similar to those of the RV group except that right heart pressure were lower in the RV group, which was related to the preoperative condition of the pulmonary circulation. In the RV group, the fraction of ventricular forward flow of the total forward flow in the main pulmonary artery ranged from 0.21 to 0.46 and was not correlated with cardiac output or with any other parameter. The backward flow into the inferior vena cava at ventricular systole was greater than the atrial flow in two patients in whom cardiac output was less than 2.2 l/min/m2, whereas caval backward flow at atrial contraction was greater than ventricular flow in the other five patients, of whom four had a cardiac output greater than 3.1 l/min/m2. CONCLUSIONS: We conclude that the inclusion of right ventricle in the circulation of the Fontan procedure does not necessarily improve overall hemodynamics in most patients.

Adult↗
PubMed1991

Fetal cardiovascular morphology of truncus arteriosus with or without truncal valve insufficiency in the rat.

BACKGROUND: Recent advances in fetal echocardiography have necessitated further study on fetal in situ cardiovascular morphology of truncus arteriosus and the effects of truncal valve insufficiency. METHODS AND RESULTS: We studied 55 fetal rats with truncus arteriosus among 300 fetuses from 40 virgin females treated with 200 mg fertilysin on the 10th day of pregnancy. After rapid whole-body freezing on the 21st day, the fetuses were studied by means of serial cross-sectional photographs of the frozen thorax. Thirty-five fetuses with a normal heart treated with fertilysin served as controls. Truncus arteriosus was characterized by a large ventricular septal defect, a solitary artery (truncus arteriosus) overriding the ventricular septum, the right and left pulmonary arteries originating from the truncus arteriosus with or without a common trunk (main pulmonary artery), and absent ductus arteriosus. Fetuses with truncal valve insufficiency had thick truncal valves, a large truncus arteriosus, and large ventricles. The subgroup of 12 fetuses with a large truncus (truncal diameter greater than 160% of the ascending aorta diameter in the controls) showed significantly greater values for right ventricular volume (200% of control) and mass (120% of control), left ventricular volume (170% of control) and mass (110% of control), right (120% of control) and left (110% of control) atrial volume, and pericardial fluid (140% of control) than the controls. These changes were less prominent and ventricular volumes were not increased in the remaining subgroup with a truncal diameter of 160% or less of aorta diameter in the controls. CONCLUSIONS: In fetal truncus arteriosus, truncal valve insufficiency was associated with increased ventricular volume load and incomplete cardiac compensation in rats.

Abnormalities, Multiple↗
PubMed1991

Effects of environmental hyperthermia on cardiovascular function in the rat embryo.

Effects of hyperthermia on the cardiovascular function of the mammalian embryo have not been well defined. The effect of hyperthermia on the blood flow and umbilical artery blood pressure was studied in rat embryos at gestational d 12 by using a method developed in our laboratory. When the temperature was changed from 37 to 42 degrees C, the heart rate increased by 15% (n = 33). Mean umbilical artery blood pressure, measured by a servo-null micropressure system, decreased from 0.64 +/- 0.05 to 0.53 +/- 0.04 mm Hg (n = 11), whereas blood flow velocity at the conotruncus, a measure of cardiac output, obtained by a 20-MHz pulsed Doppler ultrasound flowmeter, increased by 36 +/- 11% (n = 11). Mean umbilical artery blood flow increased by 66 +/- 13% (n = 11) and its vascular resistance, calculated by ratio analysis, decreased from 3.7 (median) to 1.8 units. These changes returned to baseline values when the temperature was returned to 37 degrees C. The change in blood pressure was different from that seen in the chick embryo, indicating that there is species difference in the hemodynamic effect.

Animals↗
PubMed1991

[Echocardiographic manifestations of excessive pulmonary artery banding in patients with transposition of the great arteries without ductal or ventricular shunt].

Recently, pulmonary arterial banding (PAB) and the Blalock-Taussig shunting operation (B-T) have been performed as a preparatory procedure for Jatene's operation for patients with complete transposition of the great arteries (TGA) without patent ductus arteriosus (PDA) or ventricular septal defect (VSD). We reviewed the echocardiographic findings of 29 patients after PAB and B-T. Four cases had abnormal catheterization data after PAB and B-T (Group 1). Twenty-five control cases with successful two-stage Jatene's operation exhibited normal data (Group 2). We studied 1) the grade of distortion of the interventricular septum as the a/b ratio on two-dimensional echocardiogram (2-DE), 2) the left ventricular (LV) shortening fraction (LVSF), 3) the thickening fraction (ThF), 4) the LV posterior wall thickness in diastole (LVPWTd) on M-mode echocardiogram, and 5) the LV inflow tract (LVIT) flow pattern on pulsed Doppler echocardiogram. In Group 1, all cases revealed LVSF less than 0.19 (control group: 0.40-0.56), ThF less than 0.18 (control group: 0.43-0.81), the a/b ratio higher than 0.88 (control group: 0.53-0.79), and LVPWTd thicker than 0.67 cm (control group: 0.45-0.59 cm). These data are markedly deviated from the range of the control data (p < 0.01). All cases in Group 1 had LVIT flow lacking the rapid filling phase, which was recognized in the control group. These abnormal echocardiographic findings suggest LV failure in adaptation against excessive after-load due to very tight PAB, and these figures are very different from the control group. These unusual postoperative cardiac abnormalities can be detected noninvasively using 2-DE and Doppler echocardiography.(ABSTRACT TRUNCATED AT 250 WORDS)

Echocardiography↗
PubMed1990

Characteristics and natural history of abnormal atrial rhythms in left isomerism.

The object of this study is to document variation in atrial pacemaker rate and P-wave axis, and to clarify the natural history of abnormally slow atrial rhythms in left isomerism. Standard 15-lead electrocardiograms of 50 patients with left isomerism were retrospectively studied. On the average, 9 electrocardiograms covering 7 years for each patient were available. For comparison, atrial rhythms in patients with right isomerism and in those with situs solitus and 5 representative congenital cardiac conditions were studied with the same study protocol. In left isomerism, atrial rhythm with constantly normal P-wave axis was exceptional and the presence of atrial rhythm with abnormal P-wave axis was the rule. The most frequent abnormal mean frontal P-wave axis was between -30 and -90 degrees, recorded in 70%. Slow atrial rates below the second percentile were observed in 50%, either transiently and recurrently (in 40%), or persistently (in 10%), and were associated with junctional escape in 42%. The number of patients with slow atrial rate increased with age. In right isomerism, multiple atrial rhythms were also frequent, but slow atrial rhythms was present in only 4%. Multiple atrial rhythms or bradycardia associated with junctional escape were rare in the group of patients with congenital heart disease and situs solitus. It is concluded that multiplicity and progressive slowing of the atrial rhythm are characteristic in patients with left isomerism.

Abnormalities, Multiple↗
PubMed1990

Ostial stenosis of the left coronary artery as a sole clinical manifestation of Takayasu's arteritis: a possible cause of unexpected sudden death.

An 11-year-old girl experienced several syncopal attacks and her electrocardiogram showed ST depression with exercise. Ostial stenosis of the left coronary artery was disclosed by the coronary angiography. We suspected the coronary involvement was due to Takayasu's arteritis. On operation, aortitis in the ascending aorta involving ostium of the left coronary artery was observed. Therefore Takayasu's arteritis is considered to be one of the causes of sudden death.

Aortic Arch Syndromes↗
PubMed1990

Abnormal development of fourth aortic arch derivatives in the pathogenesis of tetralogy of Fallot.

Aortic arch (AoA) anomalies were studied in 233 patients with tetralogy of Fallot (TOF) of whom some had coexisting pulmonary atresia (PA). There was a 23% incidence of a right AoA in patients without PA, 21% in those with both PA and persistent ductus arteriosus (PDA), and 50% in those with PA and major aortopulmonary collateral arteries (MAPCAs). There was a 5% incidence of an aberrant subclavian artery in patients without PA and a 16% incidence in those with PA and MAPCAs. In this cohort an elongated ascending aorta was observed both with and without high aortic arch. These aortic arch anomalies were frequently associated with PA and MAPCAs.

Adolescent↗
PubMed1990

Transplacental cardiovascular effects of four popular analgesics in rats.

The purpose of this study is to clarify fetal cardiovascular effects of four popular analgesics administered to a maternal animal model. Clinical doses of aspirin (14 mg/kg), acetaminophen (14 mg/kg), ibuprofen (6 mg/kg), or indomethacin (0.7 mg/kg) were administered orally to near-term rats. At 1, 4, 8, or 24 hours later fetuses were delivered by cesarean section, and were fixed immediately by the whole-body freezing technique. The ductus diameter, pericardial effusion, and volume and mass of the ventricles were studied by photographing multiple planes of the heart. Fetal ductal constriction was most remarkable with ibuprofen, with the diameter decreased 70% +/- 5% (mean +/- SEM) at 1 to 8 hours. Both ventricles were dilated 60% +/- 27%, and pericardial fluid was increased 120% +/- 20%. These changes partly disappeared at 24 hours. Milder but more persistent effects were observed with indomethacin. The fetal ductus was constricted 30% at 4 to 24 hours. Pericardial fluid was increased 140% +/- 30% at 24 hours. Aspirin and acetaminophen constricted the fetal ductus 10%. In conclusion, clinical doses of ibuprofen and indomethacin constricted the fetal rat ductus and caused cardiac failure. The effects of aspirin and acetaminophen were much milder.

Acetaminophen↗
PubMed1990

Coronary artery bypass in a 15-year-old girl with pseudoxanthoma elasticum.

A 15-year-old girl with pseudoxanthoma elasticum and associated severe coronary artery disease underwent double coronary artery bypass using left internal mammary artery and saphenous vein. Preoperatively the patient had life-threatening syncope and positive treadmill test results. The postoperative course was uneventful, and the patient has been doing well for 3 years. Pseudoxanthoma elasticum is a rare disease that can cause premature coronary arterial obstructive disease in children and adolescents.

Adolescent↗